1. Field of the Invention
The invention relates to a transmission path selection method in a telecommunication network in which subscribers are interconnected through switching exchanges.
2. Description of the Related Art
In military telecommunication networks, the flexibility of the network configuration to adapt to subscriber displacement to a different switching exchange is of great tactical importance. To avoid the risk that such a telecommunication network becomes overloaded by a plurality of network management problems, a hierarchic, deterministic transmission path selection method, characterized by the code number path, cannot be used. Laid-open West German patent application DE-AS No. 17 62 807 discloses a method of searching for unoccupied connection paths in a telecommunication network, in which search messages are transmitted with a "snowball effect" (parallel target search method) over the connecting lines interconnecting the exchanges, when the called subscriber is assigned to a different exchange. The search reports (forward reports) are stored in each exchange and when the called subscriber is not assigned to a particular exchange such exchange transmits outgoing forward reports to all the other exchanges connected thereto.
Thus in the known method forward reports are transmitted via all the possible connection paths in a telecommunication network so that also a subscriber which has moved to another address (so that the location of this subscriber's device is not known before the connection is set up) can be found. As a result thereof it is also possible to effect a call set-up in a military telecommunication network in which the network structure changes continuously. On the other hand, the traffic load on the exchanges is increased when this known method is used.